GPX Viewer is a simple program to visualize a gpx file. It uses
libchamplain and cairo for the plot.
It has the following features:
- show multiple GPX files.
- show waypoints and multiple tracks per gpx file.
- highlight selected track.
- show speed vs time graph.
- show distance, duration, average, moving average, max speed, moving
 time and gps points.
- zooming.
- smoothing of speed graph.
- highlighting points in speed graph on map.
